The objective of this project is to develop a new advanced imaging system to allow visualization of small cancerous tumors in situ based on combination of two types of tissue contrast: (1) molecular contrast of deoxygenated hemoglobin associated with the function of aggressive malignancy to develop angiogenesis and consume oxygen and (2) structural contrast based on increased density of tumors relative to normal tissue. The functional contrast will be provided by the Laser Optoacoustic Imaging System (LOIS) and the structural contrast will be provided by ultrasound imaging. In the course of the two previous projects sponsored by NCI (R33CA095883, R44CA089959) we developed a clinical prototype of two-dimensional LOIS and performed feasibility testing in 36 breast cancer patients. The clinical results enabled the receipt of over $3 million in private funding for development of the commercial clinical system. On the other hand, our clinical studies showed that 3D optoacoustic imaging and correlation of LOIS with ultrasound, current FDA-approved adjuvant to X-ray mammography, will permit realization of the full diagnostic potential of the optoacoustic imaging and expedite radiologist's acceptance of LOIS as a clinical diagnostic imaging modality for breast cancer. Therefore, we propose a fast-track SBIR project to resolve technical issues associated with ultrawide-band ultrasonic transducers made of a novel piezoelectric ceramics (lead metaniobate), novel hardware, firmware and software that combines LOIS and USI systems, and finally, pilot clinical testing of the new system. The proposed 3D system will display 2D images of breast slices in real time and display the final 3D image upon execution of the translation scan along the axis along the laser beam and orthogonal to the slices. The operator will have an option of imaging in the optoacoustic mode, the ultrasound B mode or the combined mode correlating two types of tissue contrast, anatomical and functional. The present methods of medical imaging are only marginally successful in differentiating between cancerous and normal breast tumors. Optoacoustic imaging utilizes the highest known physical or chemical contrast of cancerous tissues relative to normal or benign tissue based on absorption of blood in the tumor microvessels and provides images with excellent resolution of 0.5 mm typical of ultrawide-band ultrasonic imaging. Novel PET/CT and 3D CT and MRI systems being developed do not provide real-time images and will have multimillion dollar price tags. We will utilize electronic hardware and software developed in the course of previous and ongoing R&D projects for development of a more advanced system for breast cancer. The focus of the Phase-I project will be on development, fabrication and testing of a single transducer elements capable of ultrawide-band ultrasound detection and emission of ultrasound pulses with no ringing. The Phase- II project will develop an arc-shaped linear array of novel transducers and its mechanical translation that simulates 2D array, modify firmware and software of the present system to enable dual modality operation and correlation of the two types of images, and test the system in phantoms followed by clinical evaluation in 12 patients with breast cancer. Successful accomplishment of the proposed project will motivate our investors to engage in the commercial development and the process of FDA approval.